The present invention relates to a flange forming drill means for drilling a hole through the side of a pipe or the like and for forming a flange, which encircles the hole. The drill includes a drill rod which is adapted to be mounted on a rotating power source and provided with a drill bit at the lower end. Flange forming members are mounted on the drill and after the hole has been drilled, the members are extended down below the edges of the hole by turning an adjustment member that is rotatably mounted on the drill rod for retracting and extending the members.
One such flange forming drill means is disclosed in U.S. Pat. No. 3,592,038, and that apparatus has proven itself very useful when a flanged hole is to be formed in the side of pipe e.g. for the connection of a branch pipe. For locking the flange forming members in place, either in an extended flange forming position or in a retracted or hole drilling position, it is necessary that a rotating adjustment member be secured or locked in various angular positions around the drilling axis. For this purpose the Finnish Patent Publication No. 50843 discloses a locking system, which is manually pressed in a radial direction to release the lock and permit manual rotation of the adjustment member. However, such a device is inconvenient to use because one hand must perform two simultaneous crosswise actuating movements, namely pressing the lock in radial direction while turning an adjustment cone 90.degree.. In addition to this inconvenience, the lock member and top ends of the forming pins produce a safety risk, because they project outwardly of an adjustment cone and rotate therewith. There is also another apparent safety risk, namely a possibility of injuring the fingers in the forming pins or the lock, while the adjustment cone is being gripped for the adjustment, and injury could occur if electrical current is accidentally switched on to start the drill. The risk also exists if the adjustment cone is gripped during so-called post-running of the drill.